JPS6341047B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to transistors in the semiconductor industry;
Regarding the photosensitive composition for dry development of resists such as IC and LSI and the method of forming fine patterns using the same, more specifically, the polymerized polymer contains a specific aromatic azide compound and an aromatic compound having a specific vinyl group. The present invention relates to a photosensitive composition for dry development, to which the composition is added, and a method for forming a fine pattern by coating the composition on a support and patterning it in a baking gas plasma using particle beams or electromagnetic wave irradiation. Manufacturing of electronic devices in the semiconductor industry requires
There are many processing steps, and photolithography is one of them. The commonly used photolithography process is a method using ultraviolet irradiation and requires a photosensitive material, ie, a photoresist, designed to be compatible with the exposure technique and its processing. Has a film thickness of several thousand Å
A thin film of the material to be etched, such as SiO ₂ , Si ₃ N ₄ , poly-Si, etc., is applied on a silicon wafer and a resist film is formed. After that, ultraviolet rays are irradiated through a required patterning mask, and a prescribed wet development and rinsing process is carried out. After etching the underlying thin layer, the resist is subsequently removed, the wafer is thoroughly washed and dried, and impurities are diffused and implanted from the exposed silicon area. A semiconductor device is obtained by repeating this photolithography process several times and further forming electrodes and wiring. Photoresists commonly used in the semiconductor industry include negative types, which become crosslinked and insolubilized by irradiation with ultraviolet rays, and positive types, which decompose and become solubilized. In such photo- or particle beam-sensitive resists, the non-irradiated areas are selectively dissolved and removed by an organic solvent or alkaline solution called a developer in the negative type, and the irradiated areas in the positive type are selectively dissolved and removed to form the desired pattern. can get. Commercial products of such resists include OMR (manufactured by Tokyo Ohka Kogyo Co., Ltd.), KMR (manufactured by Kodatsuku Co., Ltd.), Way Coat (manufactured by Hunt Chemical Co., Ltd.) in the negative type, and OFPR (manufactured by Tokyo Ohka Kogyo Co., Ltd.) in the positive type. AZ (manufactured by Situpre),
Examples include KMPR (manufactured by Kodatsu) and HPR (manufactured by Hunt Chemical). In addition to these, there are electron beam-sensitive resists such as OEBR (manufactured by Tokyo Ohka Kogyo Co., Ltd.), and ultraviolet light-sensitive resists such as ODUR (manufactured by Tokyo Ohka Kogyo Co., Ltd.). All of these resists are developed and rinsed after irradiation with actinic light by a wet method using an organic solvent or alkaline solution. Using the resist image thus obtained as a mask, the substrate is etched using a hydrofluoric acid-based etching solution. Also, recently, CF ₄ , CF ₄ -O ₂ system, CCl ₄ , CCl ₄
Dry etching of the surface layer of a substrate using plasma of a reactive gas such as -Ar, CCl ₄ -He, etc. has begun to be widely used. After the etching process, the resist image is removed using a stripping solution made of organic solvent, but in some cases, the wafer is exposed to oxygen gas plasma to remove ash and clean the substrate using a dry method. However, as for development, the conventional wet method is still used as described above. As mentioned above, in the conventional wet method of development and rinsing using an organic solvent, the resist swells or the solvent penetrates between the resist layer and the substrate, resulting in a decrease in the dimensional reproducibility of the resist image and a decrease in processing accuracy. This is thought to be one of the causes of a decrease in production yield. In addition, the use of organic solvents and alkaline solutions worsens the working environment, reduces safety for workers, requires waste liquid treatment, takes a long time, makes automation complicated and difficult, and causes pollution. There are various problems such as.
Furthermore, in recent years, all petroleum products have become expensive due to the soaring global price of petroleum resources, and the organic solvents used in lithography are no exception, and because of the large amounts used, they have become uneconomical. It is inevitable that the use of organic solvents will become a major problem in the future. Therefore, the present inventors expected that the above-mentioned problems would be solved at once if the wet method for development and rinsing treatment could be replaced with a dry method. As a result of intensive research aimed at drying and automating a series of lithography processes by providing a photosensitive composition that can provide a highly uniform coating film, the researchers identified a polymer and a specific aromatic azide compound. After obtaining a composition consisting of an aromatic compound having a vinyl group of The inventors have discovered that the objective can be achieved by inactivating the compound, and based on this finding, the present invention has been accomplished. That is, the present invention provides a photosensitive composition for dry development comprising a polymer, a specific aromatic azide compound, and a specific aromatic compound having a vinyl group, and a method of irradiating a desired portion of a coating film of the composition with particle beams or electromagnetic waves. Then, the aromatic azide compound and the aromatic compound only in the non-irradiated area are inactivated in the coating film,
A photosensitive composition for dry development and a method for forming a fine pattern are characterized in that the composition is then removed in a gas plasma. The present invention will be explained in detail below. Particle beams or electromagnetic waves are irradiated onto a coating film (resist layer) consisting of a polymer, an aromatic azide compound, and an aromatic compound having a vinyl group. In the case of electron beams among particle beams, patterning is performed while scanning the electron beams. However, in the case of other irradiation methods, irradiation patterning is performed through a mask. The irradiation activates the aromatic azide compound and the aromatic compound having a vinyl group in the irradiated area, which acts on the polymer in the resist, causing the polymer to have different physical properties (plasma resistance, etc.) due to crosslinking, pendanting, grafting, etc. improvement). Since the aromatic azide compound and the vinyl group-containing aromatic compound in the non-irradiated area remain unchanged, they are removed from the resist or deactivated, that is, inactivated, by heating, reduced pressure, or a combination of both. In this way, there is a large difference in plasma resistance between the irradiated and non-irradiated areas, so the non-irradiated areas are easily incinerated and selectively removed, and the irradiated areas remain intact even when placed in gas plasma. A fine pattern is formed on the substrate with little loss. As the irradiation source used in the present invention, electron beams are effective as particle beams, and ultraviolet rays, deep ultraviolet rays, and X-rays are effective as electromagnetic waves. The polymer that is a component of the composition of the present invention must have no aromatic groups in its main chain or side chain, and must be easily ashed and removed in gas plasma. Also, if you apply it and dry it,
It is also necessary that there is no viscosity. Examples of such are polymethyl methacrylate, polymethyl isopropenyl ketone, polyglycidyl methacrylate, copolymers of glycidyl methacrylate and methyl methacrylate, polyvinyl chloride, polyvinyl acetate, copolymers of vinyl chloride and vinyl acetate, Copolymer of vinyl chloride and acrylic acid, polyisopropyl vinyl ketone, polybutyl methacrylate, poly 2,3-dichloro-1-propyl acrylate, poly 1,3-dichloro-1-propyl acrylate, poly 2-chloroethyl acrylate etc. Further, the aromatic azide compound used in the present invention is represented by the following general formula.

【formula】

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【formula】

[Formula] (Here, X is -O-, -CO-, -CH ₂ -, -
S-, -SO ₂ -, -CH=CH-, -CH=CH-
CO—CH=CH—, and R ₁ represents a hydrogen atom, a halogen atom, an azide group, a lower alkyl group, or a halogenated lower alkyl group). Specifically, 4,
4'-Diazidiphenyl ether, 4,4'-Diazidiphenylmethane, 4,4'-Diazidiphenyl sulfide, 4,4'-Diazidiphenyl sulfone, 2,2'-Diazide Stilbene, 4,4'-diazidodibenzylideneacetone, 1-azidonaphthalene, 1-azidoanthracene, 1-azidophenanthrene, 1-azidopyrene, 4,4'-diazidobiphenyl, 3,3'-dimethyl -4,4'-diazidobiphenyl, etc. In the present invention, by blending an aromatic compound having a vinyl group in addition to the polymer and the aromatic azide compound, it is possible to reduce the amount of the aromatic azide compound that is sensitive to actinic radiation. Generally, there is a limit to the compatibility between a polymer and an aromatic azide compound, and it is not possible to contain a large amount of an aromatic azide compound in a polymer. If a large amount of the aromatic azide compound is contained, the aromatic azide compound will crystallize and precipitate on the coating film, making it impossible to obtain a fine pattern. In conventional ultraviolet curable resins made of a polymer and an aromatic azide compound, the aromatic azide compound is added to the polymer up to a level close to the upper limit of the allowable range in order to increase its photosensitivity. In the present invention, by adding an aromatic compound having a vinyl group to the polymer and the aromatic azide compound, it is possible not only to reduce the amount of the azide compound added, but also to further increase the sensitivity to actinic rays and to achieve a highly uniform coating film. can be formed. The aromatic compound having such a vinyl group is preferably represented by the following general formula.

【formula】

【formula】

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[Formula] (where R ₂ represents a hydrogen atom, a halogen atom, a lower alkyl group, or a halogenated lower alkyl group). Specific examples include acenaphthylene, 9-vinylanthracene, 2-vinylnaphthalene, and N-vinylcarbazole. To prepare a coating solution consisting of the polymer, an aromatic azide compound, and an aromatic compound having a vinyl group, the polymer, the aromatic azide compound, and the aromatic compound having a vinyl group are mixed with cyclohexanone, ethyl cellosolve acetate, toluene, etc. Soluble in single or mixed solvents. The coating liquid thus obtained is applied by rotation to a substrate such as a silicon wafer using a spinner set at an appropriate rotation speed to form a desired film thickness. The resist film is then placed in a warm air dryer for 15 to 30 minutes to evaporate the used solvent, obtain a resist film, and selectively irradiate with actinic radiation (particle beam, electromagnetic waves) in accordance with predetermined patterning. After inactivating the resist film by heating or reducing pressure or a combination of the two, the unchanged aromatic compound in the non-irradiated area is placed in a gas plasma device, and only the non-irradiated area is selectively removed using gas plasma. A so-called dry development process is performed. Furthermore, the inactivation treatment can also be performed within a gas plasma reactor. Examples of gases suitable for development processing include:
O ₂ , CF ₄ , CF ₄ -O ₂ system, O ₂ -Ar system, etc. can be used. Since the photosensitive composition for dry development in the present invention has a different degree of ashing in gas plasma between the active ray irradiated area and the non-irradiated area, it can be developed in a dry manner, unlike the conventional wet development process. Also, since there is no need for organic solvents or aqueous alkaline solutions in the rinsing process, (1) there is no swelling of the resist or seepage of solvents during development. That is, the dimensional stability and processing accuracy are good. (2) High resolution can be obtained. (3) Safety is improved as the working environment is not contaminated by organic solvents and alkaline aqueous solutions. (4) There is no need for waste liquid treatment, and the associated pollution is avoided. (5) It is possible to automate the development process. (6) It is economically advantageous because it does not require the use of expensive processing chemicals. There are many advantages such as. Furthermore, by replacing the introduced gas after the development process, the underlying substrate can be plasma etched, and then by replacing it with oxygen gas, etc., the resist forming the fine pattern can be ashed and peeled off. Therefore, it is also possible to automate a series of semiconductor device manufacturing processes. EXAMPLES Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto. Example 1 8 g of polyisopropenyl ketone with a molecular weight of 180,000, 2 g of N-vinylcarbazole, 0.5 g of 4,4'-diazide diphenyl ether, and about cyclohexanone.
A photosensitive solution dissolved in 80 g was applied onto a silicon wafer with a thermally oxidized film by rotating it at 3000 revolutions per minute for 30 seconds. The coating film was then dried for 20 minutes in a hot air dryer maintained at 85°C to evaporate the remaining solvent in the coating film, resulting in a highly uniform coating film. Next, we used a UV exposure device PLA520F (manufactured by Canon Inc.) equipped with a CM-250 cold mirror to
A contact exposure of 15 counts of deep ultraviolet light of 250-300 nm was performed through a resolution test mask with a 0.5 μm pattern. Next, the heated vacuum dryer was maintained at 130° C., the pressure was reduced to 6 mmHg or less, and post-baking was performed for 30 minutes. Next, the wafer was placed in a gas plasma reaction processing device OAPM-301B (manufactured by Tokyo Ohka Kogyo Co., Ltd.), and the RF output was 100 W, the frequency was 13.56 MHz, and the pressure was
Oxygen plasma was generated under the conditions of 1.0Torr, oxygen gas flow rate of approximately 100c.c./min, and table temperature of 100℃2.
Developed for minutes. As a result, an image with a resolution of 0.5 μm was obtained. Example 2 A photosensitive composition consisting of 8 g of polyisopropenyl ketone with a molecular weight of 180,000, 2 g of acenaphthylene, 0.5 g of 4,4'-diazidiphenylmethane, and about 80 g of cyclohexanone was prepared, and the same operations as in Example 1 were carried out. The same results as in Example 1 were obtained. Example 3 Polyglycidyl methacrylate 8 with a molecular weight of 90,000
A photosensitive composition consisting of g, 2 g of 2-vinylnaphthalene, 0.5 g of 4,4'-diazide diphenyl ether, and about 70 g of ethyl cellosolve acetate was prepared, and the same operation as in Example 1 was performed to obtain Example 1. obtained similar results. Example 4 8 g of polymethyl methacrylate with a molecular weight of 600,000
A photosensitive composition consisting of 0.5 g of 1-azidopyrene, 2 g of 2-vinylnaphthalene and about 100 g of toluene was prepared and the same operations as in Example 1 were carried out to obtain the same results as in Example 1. Example 5 From 8 g of poly2,3-dichloro-1-propyl acrylate with a molecular weight of 200,000, 2 g of N-vinylcarbazole, 0.5 g of 3,3'-dimethyl-4,4'-diazidobiphenyl, and about 70 g of cyclohexanone. A photosensitive composition was prepared and the same operations as in Example 1 were performed to obtain the same results as in Example 1. Example 6 A photosensitive composition consisting of 8 g of poly-2-chloro-ethyl acrylate with a molecular weight of 320,000, 2 g of acenaphthylene, 0.5 g of 4,4'-diazide diphenyl ether, and about 80 g of toluene was prepared in the same manner as in Example 1. The same operation as in Example 1 was obtained. Example 7 The photosensitive compositions shown in Examples 1, 2, 5, and 6 were exposed to 15 counts of ultraviolet light of 300 to 450 nm through a mask using an ultraviolet exposure device PLA-300 (manufactured by Canon Inc.), Example 1 below
A similar operation was performed and similar results were obtained. Example 8 Polyglycidyl methacrylate 8 with a molecular weight of 90,000
g and acenaphthylene 2g, 3,3'-dimethyl-
A resist-forming coating solution consisting of 1 g of 4,4'-diazidobiphenyl and about 70 g of ethyl cellosolve acetate was prepared, and after coating on a wafer, it was dried for 20 minutes in a hot air dryer maintained at 85°C. Next, X-ray irradiation was performed using Toshiba's X-ray tube AFX-51A-RH and X-ray generator XC-401. The target was Rh, the pumping was 0.7 kW, 20 kV, the window was beryllium, the RhLα 4.6 Å line was used, the distance between the wafer and the target was 12 cm, and the X-ray flux was 5.7 mJ/cm ² /min for irradiation of 280 mJ/cm ² . Next, baking was performed for 30 minutes in a vacuum dryer maintained at 130°C under reduced pressure of 6 mmHg or less, and Example 1
Plasma treatment was performed in the same manner as above to obtain a negative image. Example 9 The photosensitive compositions used in Examples 1, 3, 4, and 8 were applied to a wafer, dried, and then exposed to an irradiation current of 5× using a scanning electron microscope HHS-2R (manufactured by Hitachi). 10 ^-10 mμA, irradiation intensity 9.62×10 ^-6 c/
Spot irradiation with an electron beam was performed under conditions of cm ² and irradiation time of 30 seconds. Then put it in a heated vacuum dryer,
Post-baking was carried out for 30 minutes while maintaining the temperature at 130° C. under reduced pressure of 6 mmHg or less. Next, plasma treatment and development were performed in the same manner as in Example 1. As a result, an image with a width of 0.3 μm was obtained. Comparative Example 1 A resist forming coating solution was prepared consisting of 8 g of polyisopropenyl ketone with a molecular weight of 180,000, 2 g of acenaphthylene, and about 80 g of cyclohexanone. After coating on a wafer in the same manner as in Example 1, it was exposed to light and exposed to oxygen gas plasma. Developed. No image could be formed at all.

Claims (1)

[Claims] 1. A dry compound comprising a polymer, an aromatic azide compound represented by the following general formulas (i) to (ix), and an aromatic compound having a vinyl group represented by the general formulas (x) to (). Photosensitive composition for development [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Where X is -O-, -CO-, -CH ₂ -,-
S-, -SO ₂ -, -CH=CH-, -CH=CH-
CO—CH=CH—, R ₁ represents a hydrogen atom, a halogen atom, an azide group, a lower alkyl group, a halogenated lower alkyl group, and R ₂ represents a hydrogen atom, a halogen atom, a lower alkyl group, a halogenated lower alkyl group. represents a group. ] 2 A desired portion of a coating film consisting of a polymer, an aromatic azide compound represented by the following general formulas (i) to (ix), and an aromatic compound having a vinyl group represented by general formulas (x) to (). irradiating with particle beams or electromagnetic waves, inactivating the above-mentioned aromatic compound only in the non-irradiated parts, and then removing the coating film in the non-irradiated parts in gas plasma. Formation method [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Here, X is -O-, -CO-, -CH ₂ -,-
S-, -SO ₂ -, -CH=CH-, -CH=CH-
CO—CH=CH—, R ₁ represents a hydrogen atom, a halogen atom, an azide group, a lower alkyl group, a halogenated lower alkyl group, and R ₂ represents a hydrogen atom, a halogen atom, a lower alkyl group, a halogenated lower alkyl group. represents a group. 3. The method for forming a fine pattern according to claim 2, wherein the inactivation treatment of the aromatic compound is a heating treatment, a depressurization treatment, a combination of both, or the like.